Well I'm not a rose expert as far as bugs and diseases go or anything else and hopefully someone with more knowledge will chime in. I would get rid of all the dead and mottled yellow foliage- look at the roots to see if they look healthy- hose any foliage that is left and cut it all back maybe about half -spray with anything for powdery mildew,mealy,spider mites for roses. Get rid of all the old soil, wash and sterilize the pot and repot in a nice loose mix. The canes seem to look nice and green still. Since it is spring it might bounce back. Don't know what zone you are in but here I would keep it in dappled sun and gradually move to full and bring in if temps dropped too low. If new leaves start fertilize lightly with rose fertilizer. Meanwhile keep it far away from other plants and bag or burn the crappy stuff.

Hope one of the more expert people chime in because I kind of think it is salvageable.

If you bought them at a garage sale they may have just been dug up and potted and could be in some shock. Are you going to leave them in the pots or plant them? If you intend on planting them I would do it right away. Roses do best when planted in the ground. If you're going to leave them in the pots do what Carol said prune, wash and spray them. I would also find larger pots for them. Those look pretty small for a full grown rose. Taking off the diseased parts helps keep it from spreading. The white powdery stuff sounds like powdery mildew. Find a fungicide that lists that. Pruning it down will help balance out the amount of roots to the amount of top growth they have to feed. I would hold off on using any kind of fertilizer on them until you see new top growth beginning.

Glad you chimed in. I hate to see a rose die if it doesn't have to. Used to live in the north shore of Mass. and was able to grow teas and floribundas- no such luck up here except for rugosa outside. Can't even plant minis out so have to do the house thing with varying results. Have one now that reminds me of a lavender floribunda that was called Angel Face. Tomorrow the temps will get into the 60's with sun so I'll put it out in dappled light. Today it was too cold and windy-actually felt like snow. I had my winter coat back on.

They look like they weren't watered once dug up and potted, and will show stress under those conditions. I see a little powdery mildew on the bud in the first photo, the rest just look water-starved. I might ignore the powdery mildew until you can get the roses planted and rehydrated, it could be a temporary condition.

I am not an expert but I find the easiest media to use that is fast draining and works well is Miracle Grow Cactus and Palm potting soil. I would I pot them, soak them in water unless they are waterlogged and repot them in a loose, fast draining soil. I would set them in the shade and let them recover a while then I would probably cut them back by about a third unless it has new healthy growth in it.